A hydrocarbon resource may be particularly valuable as a fuel, for example, gasoline. One particular hydrocarbon resource, bitumen, may be used as a basis for making synthetic crude oil, which may be refined into gasoline by a process called upgrading. Accordingly, bitumen, for example, may be relatively valuable. More particularly, to produce 350,000 barrels a day of bitumen based synthetic crude oil would equate to about 1 billion dollars a year in bitumen. Moreover, about 8% of U.S. transportation fuels, e.g., gasoline, diesel fuel, and jet fuel, are synthesized or based upon synthetic crude oil.
In the hydrocarbon upgrading or cracking process, hydrogen is added to carbon to make gasoline, so, in the case of bitumen, natural gas is added to the bitumen. Natural gas provides the hydrogen. Bitumen provides the carbon. Certain ratios and mixes of carbon and hydrogen are gasoline, about 8 carbons to 18 hydrogens, e.g. CH3(CH2)6CH3. Gasoline is worth more then either bitumen or natural gas, and thus the reason for its synthesis.
One process for cracking the hydrocarbons is fluid catalytic cracking (FCC). In the FCC process, hot bitumen is applied to a catalyst, for example, AlO2, at 900° C. with a relatively small amount of water to form synthetic crude oil. The water may donate hydroxyl radicals, OH—, to enhance the reaction. However, the FCC process has a limited efficiency, about 70%. The residual, also known as coke, is worth far less. Moreover, coke residues stop the FCC process, and there is an increased risk of fires and explosions. The FCC process also has a poor molecular selectivity, and produces relatively high reactant emissions, especially ammonia. The catalyst used in the FCC process also has a relatively short lifespan.
Several references disclose application of RF energy to a hydrocarbon resource to heat the hydrocarbon resource, for example, for cracking. In particular, U.S. Patent Application Publication No. 2010/0219107 to Parsche, which is assigned to the assignee of the present application and incorporated herein by reference, discloses a method of heating a petroleum ore by applying RF energy to a mixture of petroleum ore and susceptor particles. U.S. Patent Application Publication Nos. 2010/0218940, 2010/0219108, 2010/0219184, 2010/0223011 and 2010/0219182, all to Parsche, and all of which are assigned to the assignee of the present application and incorporated herein by reference, disclose related apparatus for heating a hydrocarbon resource by RF energy. U.S. Patent Application Publication No. 2010/0219105 to White et al. discloses a device for RF heating to reduce use of supplemental water added in the recovery of unconventional oil, for example, bitumen.
Several references disclose applying RF energy at a particular frequency to crack the hydrocarbon resource. U.S. Pat. No. 7,288,690 to Bellet at al. discloses induction heating at frequencies in the range of 3-30 MHz. U.S. Patent Application Publication No. 2009/0283257 to Becker discloses treating an oil well at a frequency range of 1-900 MHz and no more than 1000 Watts, using a dipole antenna, for example.
U.S. Pat. No. 7,891,421 to Kasevich discloses an apparatus for in-situ RF heating. The apparatus includes a cylindrically shaped radiating element that is configured to allow the passage of fluids therethrough. A coaxial cable couples the radiating element to an RF source. A choke assembly is coupled between the radiating element and the RF source to increase transmission of RF energy to the radiating element.
Further improvements to hydrocarbon resource upgrading may be desirable, and, in particular, to in-situ hydrocarbon resource upgrading. For example, it may be desirable to increase the efficiency of the bitumen to gasoline conversion process, i.e. upgrading, by making it quicker and cheaper and with a reduced amount of additional resources. In particular, it may be desirable to recover hydrocarbon resources that may be left behind in a well that may have been capped or abandoned, for example.